The present invention is directed to devices for percutaneous renal artery denervation, particularly expandable balloons constructed of energy-conductive polymers and to methods of making and using the same.
Hypertension is a chronic medical condition in which the blood pressure is elevated. Persistent hypertension is a significant risk factor associated with a variety of adverse medical conditions, including heart attacks, heart failure, arterial aneurysms, and strokes. Persistent hypertension is a leading cause of chronic renal failure. Hyperactivity of the sympathetic nervous system serving the kidneys is associated with hypertension and its progression. Deactivation of nerves in the kidneys via renal artery denervation can reduce blood pressure, and may be a viable treatment option for many patients with hypertension who do not respond to conventional drugs.
Ultrasound, radiofrequency energy, microwave energy, direct heating elements, and balloons with heat or energy sources may be applied to a region of sympathetic nerves.
A specific method for treatment of the renal sympathetic nerves involves a percutaneous, catheter-based therapy that uses radiofrequency energy to disrupt the renal sympathetic nerves. This method involves the use of an expandable polymeric balloon having an electrically-insulating layer and an electrically-conductive layer. The balloon is advanced to the treatment site, expanded with an electrically-conductive inflation fluid, and radiofrequency energy is transmitted through the balloon via the use of, for example, an electrically-conductive metallic band disposed within the balloon. Energy is then transmitted through windows that make up the electrically-conductive layer of the balloon.
Pinhole formation has been found to be one issue that can occur during expansion and transmission of radiofrequency energy through the balloon, typically at the interface of the windows when a temperature and resultant modulus differential develops between the inner electrically-conductive low impedance layer and the electrically-insulating, high impedance layer.
There remains a need in the art for an improved renal denervation balloon that is resistant to pinhole formation, and is robust to high current densities.